1. Technical Field
Various embodiments of the present disclosure generally relate to a memory device and a method of operating the memory device, and more particularly, to a program operation of the memory device.
2. Related Art
Memory devices are classified into a volatile memory device and a nonvolatile memory device.
The nonvolatile memory device can retain its contents even when power supply is interrupted. Although read and write speeds thereof are relatively low compared to those of the volatile memory device, the nonvolatile memory device is widely used for portable electronic devices because it retains its contents regardless of whether or not it is connected to a power supply.
Examples of a nonvolatile memory device may include a read-only memory (ROM), a mask ROM (MROM), a programmable ROM (PROM), an erasable programmable ROM (EPROM), an electrically erasable programmable ROM (EEPROM), a flash memory, a phase-change random access memory (PRAM), a magnetic RAM (MRAM), a resistive RAM (RRAM), and a ferroelectric RAM (FRAM) according to the data storage scheme.
The flash memory may have a two-dimensional (2D) structure in which strings are horizontally arranged on a semiconductor substrate. Alternatively, the flash memory may have a three-dimensional (3D) structure in which strings are vertically stacked on a semiconductor substrate. As the two-dimensional (2D) structure reaches its physical scaling limit, semiconductor manufacturers are producing memory devices that include memory cells vertically stacked on a semiconductor substrate.